The phone rang before sunrise. It woke Craig Patty, owner of a tiny North Texas trucking company, to vexing news about Truck 793 - a big red semi supposedly getting repairs in Houston.

"Your driver was shot in your truck," said the caller, a business colleague. "Your truck was loaded with marijuana. He was shot eight times while sitting in the cab. Do you know anything about your driver hauling marijuana?"

Commandeered by one of his drivers, who was secretly working with federal agents, the truck had been hauling marijuana from the border as part of an undercover operation. And without Patty's knowledge, the Drug Enforcement Administration was paying his driver, Lawrence Chapa, to use the truck to bust traffickers.

At least 17 hours before that early morning phone call, Chapa was shot dead in front of more than a dozen law enforcement officers - all of them taken by surprise by hijackers trying to steal the red Kenworth T600 truck and its load of pot.

In the confusion of the attack in northwest Harris County, compounded by officers in the operation not all knowing each other, a Houston policeman shot and wounded a Harris County sheriff's deputy.